The present invention relates to a method and apparatus for protecting a flexible pipe. In particular, but not exclusively, the present invention relates to the location of a protective sleeve over an outer layer of a flexible pipe whereby a portion of flexible pipe covered by the sleeve is protected to prevent an adjacent wear hazard from damaging the outer layer as the wear hazard and flexible pipe rub together.
Traditionally flexible pipe has been utilised to transport production fluids, such as oil and/or gas and/or water from one location to another. Flexible pipe has been found to be useful in connecting a sub-sea location to a sea-level location. Flexible pipe has generally been formed as an assembly of flexible pipe body and one or more end fittings. The pipe body is conventionally formed as a combination of layered materials that form a pressure-containing conduit. The pipe structure allows large deflections in use without causing bending stresses that impair the pipe's functionality over its lifetime. The pipe body is generally built up as a combined structure including tubular metallic and polymer layers which are typically unbonded.
Such unbonded flexible pipes have been used for deep water (less than 3300 feet (1005.84 meters)) and ultra-deep water (greater than 3300 feet (1005.84 meters)) developments. Of course flexible pipe may also be used for shallow water applications (for example, less than around 500 meters depth) or even for on-shore (overland) applications.
From time to time it is known that flexible pipes are located on or adjacent to a wear hazard. That is to say, the flexible pipes may be located at a location where an outer surface (typically referred to as an outer sheath) of a flexible pipe will tend to rub or knock against a nearby object. For example, the wear hazard may be a rocky seabed or a riser touchdown location or clash area or pipeline crossing zone or contact surface on a buoyancy element. A wear hazard is also generated where a jumper is laid on a Mid Water Arch (MWA) and a friction collar used to withstand axial loads and isolate goosenecks from service loads generated by movement of a Floating Production Storage and Offloading (FPSO) system. Although almost no axial relative displacement will happen due to the presence of the friction collar, significant relative displacements may happen due to sideways movement of the FPSO and the floating device as well as the effects of current that may drag lines. This relative displacement may cause the flexible riser outer sheath to breach after significant rubbing. This could potentially expose tensile armour wires to a direct contact situation with a MWA pontoon which will not be covered with any sort of polymeric sheath but rather may merely be painted with a few millimeters of epoxy-based paint.
A solution for this problem has been to include an additional sacrificial layer outside an outer sheath of a flexible pipe along the whole length of the pipe. However, such a solution introduces an increased stiffness and cost to the manufacture of flexible pipe.
It is an aim of the present invention to at least partly mitigate the above-mentioned problems.
It is an aim of certain embodiments of the present invention to provide a localised solution to problems caused to a flexible pipe by an adjacent wear hazard.
It is an aim of certain embodiments of the present invention to provide an apparatus and method for protecting an outer layer of a flexible pipe.
It is an aim of certain embodiments of the present invention to provide a method and apparatus for protecting an outer sheath of a flexible pipe in a way that can be retro-fitted to an in-situ flexible pipe.
It is an aim of certain embodiments of the present invention to provide a solution that can be easily and rapidly fitted and, if necessary, replaceable.